{{Infobox medical condition (new) | name = Nummular dermatitis | image = Nummular dermatitits.jpg | caption = Lesions visible on outer thigh | | pronounce = | field = Dermatology | synonyms = Discoid dermatitis, Discoid eczema, Microbial eczema, Nummular eczema, Nummular neurodermatitis | symptoms = | complications = | onset = | duration = | types = | causes = | risks = | diagnosis = | differential = Dermatophytosis (Ringworm) | prevention = | treatment = | medication = | prognosis = | frequency = | deaths = }} '''Nummular dermatitis''' (commonly known as '''nummular eczema''' or '''discoid eczema''') is one of the many forms of dermatitis.<ref name=":0">{{cite journal | vauthors = Cowan MA | title = Nummular eczema. A review, follow-up and analysis of a series of 325 cases | journal = Acta Dermato-Venereologica | volume = 41 | pages = 453–460 | date = 1961-01-01 | pmid = 13881857 | doi = <!-- 102340/0001555541453460 --> }}</ref> It is characterized by round or oval-shaped itchy lesions.<ref name="WEIDMAN 58–65">{{cite journal | vauthors = Weidman AI, Sawicky HH | title = Nummular eczema; review of the literature: survey of 516 case records and follow-up of 125 patients | journal = A.M.A. Archives of Dermatology | volume = 73 | issue = 1 | pages = 58–65 | date = January 1956 | pmid = 13275125 | doi = 10.1001/archderm.1956.01550010060006 }}</ref> The name comes from the Latin word "nummus," which means "coin."
==Signs and symptoms== Nummular dermatitis is characterized by chronic or relapsing itchy coin-sized ovoid-shaped red plaques.<ref>{{cite journal | vauthors = Adachi A, Horikawa T, Takashima T, Ichihashi M | title = Mercury-induced nummular dermatitis | journal = Journal of the American Academy of Dermatology | volume = 43 | issue = 2 Pt 2 | pages = 383–385 | date = August 2000 | pmid = 10901730 | doi = 10.1067/mjd.2000.102457 }}</ref><ref>{{cite journal | vauthors = Rollins TG | title = From xerosis to nummular dermatitis. The dehydration dermatosis | journal = JAMA | volume = 206 | issue = 3 | pages = 637 | date = October 1968 | pmid = 5695586 | doi = 10.1001/jama.1968.03150030093022 }}</ref> They can occur on the trunk, limbs, face, and hands.<ref name=":0" /><ref name="WEIDMAN 58–65"/><ref>{{cite journal | vauthors = Perry AD, Trafeli JP | title = Hand dermatitis: review of etiology, diagnosis, and treatment | journal = Journal of the American Board of Family Medicine | volume = 22 | issue = 3 | pages = 325–330 | date = 2009-05-01 | pmid = 19429739 | doi = 10.3122/jabfm.2009.03.080118 | doi-access = free }}</ref>
== Causes == Many contact sensitizers or irritants are known to cause contact dermatitis superimposed on nummular dermatitis. Studies have implicated nickel, cobalt, chromate, and fragrance as likely culprits.<ref name=":1" /><ref>{{cite journal | vauthors = Bonamonte D, Foti C, Vestita M, Ranieri LD, Angelini G | title = Nummular eczema and contact allergy: a retrospective study | journal = Dermatitis | volume = 23 | issue = 4 | pages = 153–157 | year = 2012 | pmid = 22828253 | doi = 10.1097/der.0b013e318260d5a0 | s2cid = 446758 }}</ref> Xerosis, or dehydration of skin is also a likely cause.<ref name=":2">{{cite journal | vauthors = Williams HC | title = Clinical practice. Atopic dermatitis | journal = The New England Journal of Medicine | volume = 352 | issue = 22 | pages = 2314–2324 | date = June 2005 | pmid = 15930422 | doi = 10.1056/NEJMcp042803 }}</ref> Infection with ''Staphylococcus aureus'' bacteria or ''Candida albicans'' may also play a role.<ref name=":2" />
== Diagnosis == Diagnosis of nummular dermatitis is largely via clinical observation. Biopsies are typically not necessary, and cannot be used to rule out other atopic dermatitis or other eczemas.<ref>{{cite journal | vauthors = Kulthanan K, Samutrapong P, Jiamton S, Tuchinda P | title = Adult-onset atopic dermatitis: a cross-sectional study of natural history and clinical manifestation | journal = Asian Pacific Journal of Allergy and Immunology | volume = 25 | issue = 4 | pages = 207–214 | date = December 2007 | pmid = 18402293 }}</ref><ref>{{cite journal | vauthors = Julián-Gónzalez RE, Orozco-Covarrubias L, Durán-McKinster C, Palacios-Lopez C, Ruiz-Maldonado R, Sáez-de-Ocariz M | title = Less common clinical manifestations of atopic dermatitis: prevalence by age | journal = Pediatric Dermatology | volume = 29 | issue = 5 | pages = 580–583 | date = 2012-09-01 | pmid = 22469300 | doi = 10.1111/j.1525-1470.2012.01739.x | s2cid = 5339404 }}</ref> However, patch testing may be employed to rule out irritants (contact dermatitis) as a cause.<ref name=":1">{{cite journal | vauthors = Khurana S, Jain VK, Aggarwal K, Gupta S | title = Patch testing in discoid eczema | journal = The Journal of Dermatology | volume = 29 | issue = 12 | pages = 763–767 | date = December 2002 | pmid = 12532040 | doi = 10.1111/j.1346-8138.2002.tb00219.x | s2cid = 43205871 }}</ref><ref>{{cite journal | vauthors = Krupa Shankar DS, Shrestha S | title = Relevance of patch testing in patients with nummular dermatitis | journal = Indian Journal of Dermatology, Venereology and Leprology | volume = 71 | issue = 6 | pages = 406–408 | date = 2005-11-01 | pmid = 16394482 | doi = 10.4103/0378-6323.18945 | doi-access = free | hdl = 1807/5587 | hdl-access = free }}</ref> In children, nummular dermatitis is commonly confused with tinea corporis.<ref name=":2" />
==Treatment== One of the keys to treatment and prevention involves keeping the skin hydrated. If the condition flares up, a common treatment involves the application of topical corticosteroids.<ref>{{Cite web |title=Nummular Eczema: vs Ringworm, Causes, Symptoms, Treatment |url=https://my.clevelandclinic.org/health/diseases/22757-nummular-eczema |archive-url=http://web.archive.org/web/20260222085544/https://my.clevelandclinic.org/health/diseases/22757-nummular-eczema |archive-date=2026-02-22 |access-date=2026-02-22 |website=Cleveland Clinic |language=en}}</ref> Oral antihistamines may help lessen itching.<ref>{{Citation |last=Robinson |first=Carolyn A. |title=Nummular Dermatitis |date=2025 |work=StatPearls |url=http://www.ncbi.nlm.nih.gov/books/NBK565878/ |access-date=2026-02-22 |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=33351436 |last2=Love |first2=Lauren W. |last3=Saleh |first3=Haitham M. |last4=Farci |first4=Fabiola}}</ref> Avoidance of irritants is a common strategy. More severe cases sometimes respond to ultraviolet light treatment. If the condition occurs only during the sun-less winter months then vitamin D supplement might be an effective treatment.{{citation needed |date=November 2018}}<ref>{{Cite web |date=2023-10-26 |title=Drug-induced nummular dermatitis |url=https://dermnetnz.org/topics/drug-induced-nummular-dermatitis |access-date=2026-01-22 |website=DermNet® |language=en}}</ref>
== Epidemiology == The prevalence of nummular dermatitis in the United States is approximately 2 per 1,000.<ref>{{Cite journal| vauthors = Johnson ML, Roberts J |date=1977-01-01|title=Prevalence of dermatological disease among persons 1-74 years of age: United States|url=http://agris.fao.org/agris-search/search.do?recordID=US201302986750|journal=ADV Data Natl CTR Health Statistics|language=English}}</ref> It is considered a disease of adulthood, for it is rare in children.<ref>{{cite journal | vauthors = Krol A, Krafchik B | title = The differential diagnosis of atopic dermatitis in childhood | journal = Dermatologic Therapy | volume = 19 | issue = 2 | pages = 73–82 | date = 2006-03-01 | pmid = 16669989 | doi = 10.1111/j.1529-8019.2006.00058.x | s2cid = 42426282 }}</ref>
== See also == * List of cutaneous conditions * Sulzberger–Garbe syndrome
== References == {{Reflist}}
== External links == {{Medical resources | DiseasesDB = 33703 | ICD10 = {{ICD10|L|30|0|l|20}} | ICD9 = {{ICD9|692.9}} | ICDO = | OMIM = | MedlinePlus = 000870 | eMedicineSubj = derm | eMedicineTopic = 298 | MeshID = }}
{{Diseases of the skin and subcutaneous tissue}}
{{DEFAULTSORT:Nummular Dermatitis}} Category:Eczema